1. Field of the Invention
The present invention relates to vapor compression systems, more particularly, to a vessel disposed within such a system for containing refrigerant and having a variable storage volume.
2. Description of the Related Art
Refrigeration systems typically include, in series, a compressor, a condenser, an expansion device, and an evaporator. In operation, gas phase refrigerant is drawn into the compressor where it is compressed to a high pressure. The high pressure refrigerant is then cooled and condensed to a liquid phase in the condenser. The pressure of the liquid phase refrigerant is then reduced by the expansion device. In the evaporator the low pressure liquid phase refrigerant absorbs heat and converts the low pressure liquid phase refrigerant back to a gas. The gas phase refrigerant then returns to the compressor and the cycle is repeated.
Compressors are typically designed for the compression of gas phase refrigerant, however, it is possible for a certain amount of liquid phase refrigerant to flow from the evaporator toward the compressor. For instance, when the system shuts down condensed refrigerant may be drawn into the compressor from the evaporator, thereby flooding the compressor with liquid phase refrigerant. When the system is restarted, the liquid phase refrigerant within the compressor can cause abnormally high pressures within the compressor and can thereby result in damage to the compressor. To prevent this phenomenon from occurring, it is known to use suction accumulators in the refrigeration system in the suction line of the compressor.
Commonly used suction accumulators are mounted near the suction inlet of the compressor and separate liquid and gas phase refrigerant. As the refrigerant flows into the accumulator, the liquid phase refrigerant collects at the bottom of the storage vessel, while the gas phase refrigerant flows through the storage vessel to the compressor. Typically, a metered orifice is provided in the lower portion of the vessel to dispense a small amount of the collected liquid phase refrigerant to the compressor, thereby preventing large amounts of potentially harmful liquid phase refrigerant from entering the compressor.
Similar vessels for separating liquid and gas phase refrigerant may also be located on the discharge side of the compressor. When located on the discharge side of the compressor, such vessels are typically referred to as receivers. Examples of known suction accumulators are disclosed in U.S. Pat. Nos. 4,009,596 and 4,182,136 assigned to Tecumseh Products Company and which are hereby expressly incorporated herein by reference.